Impulse heat-sealing apparatus and heat-sealing member therefor



June 2,. 1964 l 9595:, ETAL 3,135,077

IMPULSE HEAT-SEALING APPARATUS AND HEAT-SEALING MEMBER THEREFOR Filed April 9, 1962 INVENTORS MARTiN SIEGEL SEYMOUR ZELNICK ATTORNEY a 135 077 IMPULSE nEAT-sEALusG APPARATUS AND HEAT-SEALING MEMBER mnnnron Martin Siege], Roslyn, N.Y., and Seymour Zelnick, Toms River, N..l., assignors to Weldotron Corporation, Newark, N.J., a corporation of'New Jersey Filed Apr. 9, 1962, Ser. No. 185,996

8 Claims. (Cl. 53-182) This invention relates to apparatus for forming individual sealed packages from a continuous web of heatscalable material and, more particularly, to the formatiorr of such packages by heatsealing means of the impulse heated type.

One of the objects of the invention is the provision of a heat-sealing member for a heat-sealing apparatus of the indicated type and which includes improved electrical insulating means which provide a heat-sealing member A further object is generally to provide a heat-sealing FIG. 1;

FIG. 3 is a vertical sectional view, on a larger scale, taken on line 3 -3 of FIG. 1 and with the apparatus in an operative heat-sealing position;

FIG. 4 is a perspective view of part'of the heat-sealing and cutting member of the apparatus; and

FIG. 5 is a top plan view of an apparatus according to another form of'the invention.

Referring first to FIGS. 1 to 4 of the drawings in detail, the heat-sealing and cutting apparatus 10, which is essentially a packaging machine, comprises the laterally spaced frame members 12 and 14 which support a U-shaped bracket 16 that carries a horizontal roller 18 on which a supply roll 20 of heat-scalable packaging sheet material 22 is provided, for example transparent polyethylene. The sheet material can be' manually withdrawn from the supply roll and moved in the direction of its length so that it is disposed between heat-sealing and cutting means 24 and cooperating pressure means 26, the latter being mounted on a manually movable head 28. The heatscalable sheeting material is folded longitudinally, to form superimposed layers 29 and 29a, before being wound into its roll which .is positioned so that the folded edge 30 is at the rear of the apparatus. The head 28 is pivoted at 32 to frame member 14 and is providcdwith a handle g 34 for moving the head to and from pressure applying or sealing position wherein pressure is applied on the layers of material which are engaged between the sealing means 24 and the pressure means 26.

The articles which are to be packaged in the sheet material are supported on a tray 36 and the level of the tray is adjustable to accommodate various heights of articles, For this purpose, the frame members 12 and 14 are each provided with a vertically extending slot 38 and a clamping screw 40 extends through each of the slots and is connected to a member 42 which extends down- Patented June 2, 1964 Wardly from the bottom of the tray. When the screws are tightened, the head of the screw engages the portions of the frame member adjacent slot 38 for clamping the tray at a particular level. To adjust the level of the tray, the screws are loosened to permit them to move vertically up and down in theirrespective slots.

The heat-sealing and cutting means 24 comprises a stationary heat-sealing and cutting member 44 which extends transversely of the apparatus and is secured to a transversely extending bar 46 by screws 48. Another heat-sealing and cutting member 50 extends longitudinally of the apparatus and is secured to frame member 12 a by screws 48. Transverse sealing member 44 extends from a rear position, beyond folded edge, 30 of the heata scalable material, forwardly to a position beyond the separate side edges 52 and 54 of the material to seal and separate a portion of the material at sealing member 44 from the supply roll 20. Sealing member 50 extends longitudinally of the apparatus and has one of itsends in abutment with transverse sealing member 44 at a position which is intermediate the ends of the latter member to I seal and cut the material along a longitudinal line which extends from member 44 in a direction toward the tray end of the apparatus.

The heat-sealing and cutting members 44 and 50 are similar in construction. Each comprises an elongated bar 56 of a good heat-conducting material, for example aluminum, which is of relatively large mass so that it can quickly absorb and conduct heat for, rapidly cooling the impulse-heated sealing and cutting element 58 when the heating current is interrupted. The bar has a longitudinally extending groove 60 which is co-extensive therewith and has a cross section which is in the form of a mortise of a dovetail. More particularly, the lateral- 1y spaced side walls 62 of the groove diverge from each other in a downward direction from the top of the groove to the bottom thereof.

A series of separate ceramic electrical insulators 64, made of alumina oxide, for example, extend longitudinally in the groove in end-to-end abutting relation. Each insulator is in the form of block which has longitudinally spaced parallel end walls 66 which extend perpendicularly between the laterally spaced parallel top 68 and bottom 70 of the block. The laterally spaced side walls 72 of the block extend longitudinally between the end walls 66 and diverge from the top 68 to the bottom 70 in the same amount as the corresponding side walls 62 of groove 60. It is to be observed that the cross section of insula-- tors 64 is in the form of a tenon of a dovetail so that the insulators can be inserted endwise into the longitudinal so that a continuous longitudinal groove is formed in each of the heat-sealing and cutting members 44 and 50 which is co-extensive with the corresponding member. A thin elongated heat-sealing and cutting, ribbon-like, element 76 and 78 is positioned in the corresponding groove formed by insulators 64 of sealing members 44 and 50. respectively, and the sides of the element are in longitudinal sliding contact with the side walls of the groove to permit the element to freely expand and contract lengthwise in the groove. The sealing elements 76 and 78 are made of a metal which has a high electrical resistance, for example a nickel-chromium alloy steel, which is also resistant to high temperatures. Ribbons of about between .010" to .020" thickness have been found to give good results. The elements project outwardly from the 3 to expose a thin heat-sealing and cutting edge 80 (FIG. 3

One end of each or" the sealing elements 76 and 78 is provided with an electrical terminal 82 to which a lead 84, in the case of element 78, and a lead 86 in the case of element 76, is connected to provide the heating current for the corresponding element. A tension spring '87 has one of its ends connected to terminal 82 and its opposite end affixed to an electrically nonconducting member 88 which is connected to frame member 12, in the case of member 50, and to bar 46 in the case of member 44. Member 88 is L-shaped and the short leg of the member covers part or the corresponding end of groove 60 to retain the insulators 64 in the groove.

As best seen in FIG. 2, the non-terminal end of sealing member Stl'abuts against the side of sealing member 44, at a position intermediate the ends of the latter member. The non-terminal end of sealing element 78 extends from the end of bar 56 of member 50, and extends through a slot 90 provided in the side of the bar 56 of member 44, and is bent 90 so that it extends longitudinally of element 76 in contact therewith for a short distance. It is bent again 90 so that it extends in a direction parallel to itself through another slot 92 provided in the side of bar 56 of member 44 and is clamped in position between the side of member 50 of the side of frame member 112. In this manner, the non'terminal end of sealing element 78 is fixed against movement and is in electrical contact with sealing element 76.

The non-terminal end of sealing element 76 extends from the corresponding end of bar 56 of member 44 and is bent 90". An electrical insulating member 94 extends across said end of the bar to retain the insulators 64 in position in the corresponding groove 60 and the bentportion of element 76 is fixed in position between insulating member 94 and an electrically conducting plate 96, with which it is in electrical contact and to which an electrical lead 98 is connected for providing heating current to element 76.

The heating elements 76 and '78 are grounded at the position at which they are in abutment with each other due to the engagement of the non-terminal end of element 78 with the grounded frame member 12. The terminal end of element 78 is provided with a grounded source of voltage (not shown) through lead 84. Both ends of sealing element 76 are connected to the terminals of another and separate source of voltage (not shown) through the corresponding leads 86 and 98. These separate sources of voltages supply a short impulse of high current to the corresponding heat-sealing and cutting element for rapidly heating it for the heat-sealing and cutting opera-= tion. The springs 87 apply tension along the length of the sealing and cutting element and thereby insure smooth expanding and contracting longitudinal movement of the element in its corresponding groove 74 and maintain the element in taut condition during said expansion and contraction. This is especially important in view of the fact that the heating current is applied to the element for a short impulse period and since it is very high and the element is thin and long, there is nearly instantaneous heating and expansion of the element. When the current impulse is interrupted, there is a rapid cooling and corresponding contraction of the element against the spring tension.

The low thermal mass of the heated element and its high electric resistance enable it to reach its sealing temperature very rapidly when current is transmitted therethrough as soon. as switch 100 is operated by the closing of head 28 into operative position. The ceramic insulators 64 are not affected by the very high temperatures of the sealing elements and can operate for long periods of time without impairment of their electrical insulating properties. The current supplied to the heating elements 76 and 78 results in the rapid heating thereof and yet the large thermal mass of the bars 56 results in the maintenance of low temperatures for the other parts of the sealing members 44 and 50. This also has the eifect of rapidly cooling the heating element between current pulses so that improved pressure sealing is obtained without impairment of the heat-sealed edges ,of the package when head 28 is held in operative position after the current pulse is terminated under the control of a timer (not shown) operated by switch 100. The ceramic insulators permit the sealing elements to be rapidly heated and yet are thin enough to allow the flow of heat therefrom to bar 56 between heat pulses. Preferably, the thickness of the ceramic material at each side of the ribbon is about onesixteenth of an inch and the overall height of the insulators is about three-sixteenths of an inch. Groove 74 is about one-eighth of an inch deep. It will be noted further that bar 56 acts as a heat sink by reason of its owi. large thermal mass and that since the frame of the machine is made of metal and is in thermal-conductive relation with said bar, additional thermal conduction takes place, if needed, to prevent excess heating of the bar.

The pressure-applying means 26 is made of a suitable heat-resistant and electrically non-conducting resilient material, for example silicon rubber, and is in the form illustrated to provide confronting surfaces 102 which act as an abutment for the cutting and sealing edges of elements 76 and 78.

In the use of the apparatus, the heat-scalable material 22 is withdrawn from its roll 20 and placed between the heat-sealing and cutting means 24 and the pressure applying means 26. Head 28 is moved into operating position which operates switch and impulse-heating current is I passed through the sealing and cutting elements 76 and 78 for a predetermined period of time, as determined by the time; (not shown), to seal and cut the material simultaneously along a transverse line which extends from the folded edge 30 of the material to edges 52 and 54 and along a line which extends from said transverse line in a longitudinal direction opposite folded edge 30 and in a direction toward the tray end of the apparatus. This sealing and cutting operation separates the portion of the material, which extends from transverse member 44 toward the tray end of the apparatus, from the supply roll 20 and this separated material is sealed along a transverse line and along a longitudinal line which is opposite folded edge 30. The portion of the material, which is still integral with roll 20, now has a forward transverse edge which is sealed. The material is further unwound and the forward transverse sealed edge is moved longitudinally of the apparatus between the pressure applying means 24 and the sealing and cutting means 26. The article A, which is to be packaged, is inserted between the layers 29 and 29a of the material, through the separate side edges 52 and 54, and the operating head is again moved into operative position to form a completely sealed package and simultaneously separate it from the supply roll 20.

It is to be observed that with each operation of the apparatus, the transverse rear sealed edge of a package'is formed concurrently with the sealing of the forward transverse edge of the next package which is to be formed. All trim material which extends from sealing member 50 to the side edges 52 and 54 of the material is removed concurrently with the completion and separation of the package from the supply roll 20. The fact that heatsealing and cutting member 44 extends beyond the side edges 52 and 54 of the material insures that completely sealed transverse edges are always formed which extend transversely of the material from one side edge to its opposite side edge. This eliminates the necessity of accurate transverse positioning of the material with respect to sealing member 50 which was necessary to avoid formation of packages which have unsealed corners, which may occur when members 44 and 50 form an L and member 44 does not extend beyond the side edges 52 and 54 of the material.

As indicated above, the provision of separate insulators I 64 enables the heat-sealing and cutting members to be easily formed with curved portions, as shown in FIG. 5. In this form of the invention, the heat-sealing and cutting members 104 and 106 are in the form of a semicircle and are utilized to form circular packages, although it will be understood that the sealing members can have any curved form. The members are suitably supported on a plate 108 which is secured to the side frame members of the apparatus. Each end of the sealing members is provided with a terminal connection 82 and a tension spring 87, as previously described with respect to FIG. 2. The forward sealing member 104 is utilized tocomplete the rear portion of a package and the rear sealing member 106 is'utilized to simultaneously form the forward portion of another package, which is positioned rearwardly of the first mentionedpackage. To complete the rearward portion of the latter package, the material is moved longitudinally forwardly, away from the supply roll 20 of the apparatus, so that the rear portion of the package which is to be completed. is placed at the position of member 104. Upon downward movement of head 28 into sealing position, the rear portion of the forward package is completed concurrently with the formation of the forward portion of another package', which is rearwardly of the just completed package. It is to be observed that the completion of the rear portion of the package results in its separation from the supply roll 20, and that with sealing members of semicircular configuration, it is not necessary that the plies of material be joined along a side edge, as was true with the sealing members shown in FIG. 1. The pressure applying means 26 for members 104 and 106 obviously have formations corresponding to the configuration of said members. Preferably, the heat-sealing and cutting members 104 and 106 aresomewhat longer than semicircles in order that the packages may be completely sealed without precision design of the members in relation to each other and without precise positioning of thematerial with reference to the members.

It will be understood that it is within the scope of the invention to mount the sealing and cutting members on the movable head 28 of the apparatus and the pressure means 26 on the stationary frame member 12 and bar 46,

Certain features shown herein but not claimed are also shown and described in our corresponding co-pending application Serial No. 114,588 filed May 2, 1961, now

' US. Patent No.'3,047,991 issued August 7, 1962.

While we have shown and described the preferred embodiment of the invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

What is claimed is: I

1'. A heat-sealing and cutting member for simultaneously sealing and cutting heat-scalable material, said member comprising:

(a) an elongated bar of heat conducting material of relatively large mass and having a longitudinally extending groove,

(b) a series of separate ceramic members mounted in said groove in end-to-end relation and extending 1ongitudinally thereof,

(c) each of said members having a longitudinally extending groove in alignment with the longitudinally extending groove of the adjacent member, and

(d) a relatively thin elongated heat-sealing and cutting element mounted in said last mentioned grooves for longitudinal sliding expansion and contraction movement therein and having a longitudinal edge extending from said last mentioned grooves for the heatsealing and cutting operation,

(e) said element being made of electrically resistant and heat-conducting material.

2. A heat-sealing and cutting member for simultaneously sealing and cutting heat-scalable material, said member comprising: 7 a

(a) an elongated bar of heat conducting materialof relatively large mass and having a longitudinally extending groove,

(b) said groove having side walls diverging outwardly from the top of the groove to the bottom thereof, (0) a series of separate ceramic members mounted in said groove in end-to-end relation and extending longitudinally thereof, (d) each of said members having side walls in sliding longitudinal engagement with said side walls of said groove and diverging outwardly from the top of said groove to the bottom thereof to prevent said members' from being removed from said groove through the top thereof, (e) each of said members having a groove extending longitudinally of said member from one end thereof to its opposite end,

(f) each groove of each member being in alignment with the groove of the. adjacent member to form a,

groove extending longitudinally of said bar, and a (g) a heat-sealing and cutting element in the form of'a.

ribbon of high temperature and high electrically resistant metal mounted in said last mentioned groove for longitudinal sliding expansion and contraction movement therein and having a longitudinal edge extending from said last mentioned groove for the heatsealing and cutting operation.

3. A heat-sealing and cutting member for simultan'e' t I ously sealing and cutting heat-scalable material, said member comprising:

(a) an elongated 'bar of heat conducting material of relativelylarge mass and having a longitudinally extending groove, (b) a series of separate non-electrically conductin members mounted in said groove in end-to-end rela-.

tion and extending longitudinally thereof,

(c) each of said members having a longitudinally extending groove in alignment with the longitudinally extending groove of the adjacent member, and

(d) a relatively thin elongated heat-sealing and cutting element mounted in said last mentioned groove for longitudinal sliding expansion and contraction movement therein and having a longitudinal edge, extend:

ing from said last mentioned groove for the heatsealing and cutting operation,

(e) said element being made of electrically resistant and heat-conducting material.

4. A heat sealing and cutting member for' simultaneously sealing and cutting heat-scalable material, said member comprising: j

(a) an elongated bar of heat-conducting material of relatively large mass and having afllongitudinally H extending groove, (b) said groove having side walls diverging outwardly from the top of the groove to the bottom thereof, (c) a series of separate non-electrically conducting members mounted in said groove in end-to-end relation and extending longitudinally thereof,

(d) each of said members having side walls in sliding longitudinal engagement with said side walls of said groove and diverging outwardly from the top of said groove to the bottom thereof to prevent said members from being removed from said groove through v the top thereof,

(e) each of said members having a groove extending longitudinally of said member from one end thereof to its opposite end,

(f) each groove of each member being in alignment with the groove of the adjacent member to form a. groove extending longitudinally of said bar, and

: ribbon of high temperature and high electrically resistant metal mounted in said last mentioned groove for longitudinal sliding expansion and contraction movement therein and having a longitudinal edge extending from said groove'for the heat-sealing and cutting operation.

5. A heat-sealing and cutting member for simultaneously sealing and cutting heat-sealable material, said member comprising:

(a) an elongated bar of heat conducting material of relatively large mass and having a longitudinally extending arcuate groove,

,(b) a series of separate non-electrically conducting members mounted in said groove in end-to-end relation and extending longitudinally thereof,

() each of said members having a longitudinally extending groove in alignment with the longitudinallyv extending groove of the adjacent member, and

(d) a relatively thin elongated heat-sealing and cutting element mounted in said last mentioned grooves for longitudinal sliding expansion and contraction movement therein and having a longitudinal edge extending from said last mentioned grooves for the heatsealing and cutting operation,

(c) said element being made of electrically resistant and heat-conducting material.

6. A heat-sealing and cutting member for simultaneously .sealing and cutting heatasealable material, said member comprising:

(a) an elongated bar of heat conducting material of relatively large mass and having a longitudinally extending arcuate groove,

(b) said groove having side walls diverging outwardly from the top of the groove to the bottom thereof,

(0) a series of separate non-electrically conducting members mounted in said groove in end-toend relation and extending longitudinally thereof,

(d) each of said members having side walls in sliding longitudinal engagement with said side walls of said groove and diverging outwardly from the top of said groove to the bottom thereof to prevent said members from being removed from said groove through the top thereof,

(2) each of said members having a groove extending longitudinally of said member from one end thereof to its opposite end,

(1) each groove of each member being in alignment with the groove of the adjacent member to form a groove extending longitudinally of said bar, and

(g) a heat-sealing and cutting element in the form of a ribbon of high temperature and high electrically resistant metal mounted in said last mentioned groove for longitudinal sliding expansion and contraction movement therein and having a longitudinal edge extending from said last mentioned groove for the heat-sealing and cutting operation.

7. Heat-sealing apparatus of the heat pulse type for sealing and simultaneously cutting heat-scalable sheet material, comprising a heat-sealing and cutting ribbon of high temperature and high electrical resistance metal adapted to be pulse-heated by an electrical current passed therethrough, means for supporting said ribbon with a side edge thereof positioned to engage the heat-sealable material for both the sealing and cutting operation when said ribbon is pulse-heated, said supporting means hav- 8 ing provision for the longitudinal expansion of said ribbon when it is pulse-heated and for the longitudinal contraction of the ribbon between heating pulses, said supporting means having a groove with spaced side walls between which said ribbon is mounted for movement longitudinally of said groove when said ribbon expands and contracts, a series of ceramic insulating members positioned in endto-end relation in said groove and extending longitudinally thereof and for holding saidfribbon against movement transversely of said groove, each of said insulating members having a longitudinally extending groove, the opposite sides of said ribbon being in sliding engagement with the opposite sides of the grooves of said members longitudinally of the ribbon, and means operatively connected to said ribbon for maintaining said ribbon in taut condition longitudinally thereof during its expansion and contraction on said supporting means in said slidable engagement with said ceramic insulation, said supporting means having a large thermal mass inrelation to the thermal mass of said ribbon for rapid cooling of the ribbon between heat pulses.

8. Apparatus for forming sealed packages of heat-sealable material, comprising a heat-sealing and cutting memher, a cooperating pressure member, means mounting said members for relative movement toward each other for applying pressure to said heat-scalable material interposed between said members for the cutting andheat-sealing operation, said heat-sealing and cutting member comprising an elongated bar of heat-conducting material having a longitudinally extending groove coextensive therewith, a series of ceramic heat insulating and electrically nonconducting members disposed in end-to-end relation in said groove and extending longitudinally thereof, each of said members having a relatively narrow longitudinally extending groove in alignment with the grooves of the adjacent members to form a relatively narrow longitudinally extending groove coextensive with said bar, a relatively thin elongated heat-sealing and cutting element of electrically high resistant material mounted for sliding expansion and contraction movement longitudinally in said last mentioned groove and having a portion projecting from said ceramic members to expose a heat-sealing and cutting edge, the opposite sides of said heat-sealing and cutting element being in sliding engagement with the opposite sides of said last mentioned groove, and spring means secured to said element for supplying a tension force longitudinally thereof to maintain said element in taut condition in said groove during longitudinal sliding 7 expansion and contraction movement of said element in said last mentioned groove.

References Cited in the file of this-patent UNITED STATES PATENTS 

8. APPARATUS FOR FORMING SEALED PACKAGES OF HEAT-SEALABLE MATERIAL, COMPRISING A HEAT-SEALING AND CUTTING MEMBER, A COOPERATING PRESSURE MEMBER, MEANS MOUNTING SAID MEMBERS FOR RELATIVE TOWARD EACH OTHER FOR APPLYING PRESSURE TO SAID HEAT-SEALABLE MATERIAL INTERPOSED BETWEEN SAID MEMBERS FOR THE CUTTING AND HEAT-SEALING OPERATION, SAID HEAT-SEALING AND CUTTING MEMBER COMPRISING AN ELONGATED BAR OF HEAT-CONDUCTING MATERIAL HAVING A LONGITUDINALLY EXTENDING GROOVE COEXTENSIVE THEREWITH, A SERIES OF CERAMIC HEAT INSULATING AND ELECTRICALLY NONCONDUCTING MEMBERS DISPOSED IN END-TO-END RELATION IN SAID GROOVE AND EXTENDING LONGITUDINALLY THEREOF, EACH OF SAID MEMBERS HAVING A RELATIVELY NARROW LONGITUDINALLY EXTENDING GROOVE IN ALIGNMENT WITH THE GROOVES OF THE ADJACENT MEMBERS TO FORM A RELATIVELY NARROW LONGITUDINALLY EXTENDING GROOVE COEXTENSIVE WITH SAID BAR, A RELATIVELY THIN ELONGATED HEAT-SEALING AND CUTTING ELEMENT OF ELECTRICALLY HIGH RESISTANT MATERIAL MOUNTED FOR SLIDING EXPANSION AND CONTRACTION MOVEMENT LONGITUDINALLY IN SAID LAST MENTIONED GROOVE AND HAVING A PORTION PROJECTING FROM SAID CERAMIC MEMBERS TO EXPOSE A HEAT-SEALING AND CUTTING EDGE, THE OPPOSITE SIDES OF SAID HEAT-SEALING AND CUTTING ELEMENT BEING IN SLIDING ENGAGEMENT WITH THE OPPOSITE SIDES OF SAID LAST MENTIONED GROOVE, AND SPRING MEANS SECURED TO SAID ELEMENT FOR SUPPLYING A TENSION FORCE LONGITUDINALLY THEREOF TO MAINTAIN SAID ELEMENT IN TAUT CONDITION IN SAID GROOVE DURING LONGITUDINAL SLIDING EXPANSION AND CONTRACTION MOVEMENT OF SAID ELEMENT IN SAID LAST MENTIONED GROOVE. 